(1) Field of the Invention
The present invention relates to a removable lift assembly for a rotorcraft and to a rotorcraft including such a lift assembly.
(2) Description of Related Art
A rotorcraft has at least one rotor, sometimes referred to as its “main rotor”, that provides the rotorcraft with at least some of its lift, and possibly also with its propulsion.
Such a main rotor may be set into rotation by a power plant comprising at least one engine and a main gearbox (mgb). The main gearbox is connected to a hub of the main rotor by a rotor mast and to at least one engine by a power drive train.
The engine thus sets the main gearbox into motion and the main gearbox drives rotation of the main rotor.
The main gearbox and the engine of a power plant are supported by a floor of the aircraft sometimes referred to as a “transmission support platform”.
For example, the main gearbox comprises a casing extending in elevation from a bottom to a top.
The top may be connected to the transmission support platform via at least three bars sometimes referred to as “suspension bars”.
Furthermore, a suspension system may extend between the transmission support platform and the bottom of the main gearbox.
Such a suspension system may comprise a bar extending between two ends. A laminated damper is arranged between each end of the bar and the main gearbox. In addition, a laminated damper is arranged between each of the bars and the transmission support platform.
The bar shape explains why such a suspension system is sometimes referred to as a “dog-bone” suspension system (“os a chien” in French language).
Document FR 1 507 306 describes another suspension system that has a plate with slots. That particular shape explains why that suspension system is sometimes referred to as a “barbecue” suspension system.
The transmission support platform might be located above the master cross-section of the fuselage of the rotorcraft, which tends to degrade the drag of the rotorcraft.
The transmission support platform might alternatively be incorporated at least in part with the master cross-section in order to minimize the drag of the rotorcraft. Nevertheless, such an arrangement reduces the ground clearance of the blades of the main rotor. On a rotorcraft that is provided both with a rotor and with propellers, it can then be difficult to arrange the propellers under the main rotor for the purpose of contributing in particular to propelling the rotorcraft and/or to controlling yaw movement of the rotorcraft.
A rotorcraft may have a rotor as well as propellers arranged on a wing in order to reach high forward speed. Nevertheless, it can be understood that the presence of a wing carrying propellers can be constraining in terms of overall size, for example when the rotorcraft is transported on board a ship.
By way of example, document us 2002/0011539 describes a rotorcraft having a main rotor and two propellers. The two propellers are fastened respectively to the trailing edges of two half-wings extending transversely on either side of the fuselage.
The rotor mast is then very long in order to avoid contact between the blades of the main rotor and the blades of the propellers. Such an arrangement can have a negative impact on the drag generated by the rotorcraft in forward flight.
Furthermore, a wing is usually fastened to the fuselage in non-removable manner.
Document us 2011/0266398 describes a system for fastening a wing to a fuselage, the fastener system being provided with a plurality of fastener means.
Document RU 2 448 866 describes a device for connecting a wing to a fuselage.
Document FR 2 935 351 is remote from the specific technical field of rotorcraft and provides no teaching for this technical field.
Document FR 2 935 351 describes an airplane having a fuselage suspended under a wing carrying a tail assembly and jets. The purpose of that architecture is to improve the situation of transport airplanes relative to problems of centering and setting the wing.
That document therefore does not belong to the technical field of the invention, namely the technical field of rotorcraft having high forward speeds.
Also known are the following documents: EP 2 690 011, GB 895 590, and GB 673 421.